If the deal is approved outright, it will be a green light to Comcast to make a formal bid for Fox assets—a vertical merging of distribution and content similar to AT&T-Time Warner.

Comcast’s bid, which is reportedly planned as a $60 billion all-cash offer, would top Disney’s $52.4 billion all-stock offer. Disney would then sweeten its bid and a high-stakes battle would ensue, driving up the value of Fox.

Of course, the Justice Department may still object to a Comcast acquisition of Fox assets even if it loses its case against AT&T. But it would have a much harder time blocking the deal.

Alternately, if the U.S. government wins its case against AT&T, blocking the merger, it will throw cold water on Comcast’s plans. “It will embolden the Justice Department to be more forceful,” says Gene Kimmelman, a former Justice Department antitrust attorney. That would likely leave Disney the winner, even if it doesn’t raise its offer.

The messiest—and perhaps most likely—scenario is that the AT&T trial resolves somewhere in the middle, with the judge rejecting the government’s remedy and saying the deal can go through if it meets specific conditions. The Justice Department is unlikely to be pleased by that; it has been trying to get away from such remedies, which are difficult to oversee and which force it to play the role of industry regulator. It may appeal the decision.

This scenario is murky for Comcast and for Fox. It means the government will still be inclined to toughen oversight of Comcast, though how successfully is uncertain. A Fox-Disney merger could also invite scrutiny, because of the company’s control over sports programming and its power on the studio side. But these can likely be remedied without blocking a deal.

The battle would reverberate across the Atlantic, potentially pushing up the value of Sky, the satellite TV company, which is 39% owned by Fox. Right now shares trade at 13.59 British pounds, well above the current offers, but as the only option for growth in the U.K., Sky is a crucial piece in the new-media puzzle.

Mr. Murdoch will have to weigh all of this as he decides which offer to accept. Disney and Comcast will fight to the bitter end. No other media assets are as attractive as Fox’s and both companies see them as a necessity to compete globally with